organic hydroponic greenhouse crop production; by mary peet

8/8/2019 Organic Hydroponic Greenhouse Crop Production; by Mary Peet

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Mary PeetMary Peet

www.ces.ncsu.edu/greenh


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Why Grow Organic?

Organic is big business in the US ($3.5 billion)

Growth in organic produce 20%/yr for past 5 yrs.

Overexpansion of greenhouse tomato industrymay drive down prices of greenhouse tomatoes

According to the 1997 USCensus of Agriculture,

compared to 1992, the # of

greenhouse vegetable

growers was up 35%.

(annual increase of 7%)

1978 1982 1987 1992 1997

0

500

1000

1500

2000

2500

3000

Numbe

rofFarms

Year


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Area of greenhouse

vegetables was up 35%

(annual increase of 7%)

Sales wereup139% (annual

increase of 28%)

1978 1982 1987 1992 1997

0

50000

100000

150000

200000

250000

Sales($1,0

00)

Year

1978 1982 1987 1992 1997

0

50

100

150

200

250

300

350

400

haofG

reenhouseVege

tables

Year


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Types of Organic Production Systems

Water-based (NFT, pipe

systems or float trays)

Solid media in trays, slabs

or containers

Low CEC-gravel, perlite,rockwool

Organic substrates (peat, coir,

compost)

Soil-based (most common)

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Some Large Commercial Hydroponic

Operations-

Valley Fresh, Colorado


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Typical Problems using Organic

Fertilizers in Hydroponic Systems

Lack of sterility in system Diseases

Clogging from algae and other free-

living organisms

Deciding when to replace

recirculating water Relationship of EC (salt readings) to

available plant nutrients

Local, affordable sources of


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Profile of Industry No statistics, but groups

of organic greenhouse

growers in Quebec, NewEngland, California

Most grow in soil usingsame procedures as field

growers. Root diseases are

a problem, althoughcomposts may help

In south, solarizationpossible

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ur Approach to

Organic

Hydroponics:

Soilless media with

higher water andnutrient retention

than perliteand

rockwool(peat,pinebark, coir) with

added compost

Organicallycertifiable media

ingredients &

fertilizers

Biocontrolsfor ests


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No national standards-Yet!

Most groups have lists of materials that are approved,

restricted or prohibited. No genetically modified crops.

Brand-name products must be approved byO MRI(www.omri.org)

Criteria for greenhouses less well developed Some philosophical objections, e.g. not natural enough

Organic Certification in the U.S.


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Restrictions on Greenhouse Construction

General Allowed Restricted Prohibited

Transition period

may be required

if taking over

existing

conventional

greenhouseWhole house

must be

certified, but

can have

uncertified

houses o n same

farm if product

distinguishable

Proper

ventilation

required, but

emergency

use o f

portableheaters

allowed

Pressure treated

lumber only

allowed on

foundations

and end walls

(must beisolated from

growing media

and plants)

Artificial light

and shade

No asbestos,

urea, or

formaldehyde

No

biodegradable

plastic(Canada)


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Containers, Substrates

General Allowed Restricted Prohibited

Transplants

for fi eldproduction

require

organicpractices i f

available

Perlite ok,

rockwoolquestionable

Peat allowed

but compostpreferred;

Coir ok;

Recyclable

containers

(Canada)

Fiber

containerswith no

prohibited

material(NOFA,

FOG);

No synthetic

fertilizers,fungicides,

wetting agents,

or sterilants inpotting mix

Vermicompos


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Fertilization

Allowed Restricted ProhibitedCompost (N, K, Micros);

Colloidal soft rock and hard

rock phosphate (P);

Guano (P);

Wood ash (K);

Rock dusts [granite, feldspar,

greensand] (K);

Natural potassium sulfate (K);

Limestone, gypsum, calcium

oxide, (Ca);

Dolomitic limestone, Kierserite(Mg);

Kelp meal, liquid or powdered

seaweed extract, rock powders

(Micros); Commercial productson OMRI list

Sodium Nitrate (N);

Fish emulsion (N,

P);

Bone Meal (N, P);

Calcium Chloride

(Ca);

Epsom salts (Mg);

Chelate, acid

treated sulfate, or

oxide materials

(Micros)

Synthetic

Sources;

Muriate of potash;

Quick lime, or

hydrated lime

Earth Juice and

fish meal

fertilizers


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Pest Control

Allowed Restricted ProhibitedInsect Traps;

Insect Barriers;

Hand, Mechanical, or

Hydraulic Removal;

Biological Controls;

Alcohol to disinfect

benches, pots, tools

Steam sterilization, hot

water seed treatment,

low temperature bakingResistant cultivars;

Roguing or destroying

infected plants;

Herbal sprays

Oil Sprays; Insecticidal

Soaps; Bacillus

Thringiensis (BT);

Copper; Sulfur;

Approved Non-

synthetic Fungicides;

Bleach, hydrogen

peroxide and oxalic

acid for disinfection

Synthetic Pesticides,

Fungicides, and

Nematicides


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Issues before starting

commercial organic venture

Is the production system tested on tomatoes? Herbs, lettuce and transplants are not as nutrient-

demanding

Is certifying agency receptive?

Will the market pay a premium?

Is your philosphycompatible?

How do you feel about jumping through a lot of

hoops?

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Substrate:

Fafardspecial blend of 4-P to omit wetting agents,nutrient charge and micronutrients (85% by volume)

15% by volume Vermicycle(worm compost: 1.8-1.6-0.

1.5 lbs/cubic yard each of:

Blood meal

Bone meal

Potassium sulfate

O MRI-approved wetting agent Natural Wet at 2tablespoons/gal

0.5 lbs/cubic yard sulfur For other suggested potting mixes, visitwww.attra.org

Fertilization: Equivalentin all


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Fertilization: Equivalent in all

fertilizer treatments*

125 ppm N,

45 ppm P, 195 ppm K,

185 ppm Ca,

44 ppm Mg and

micronutrients

Provided at each watering (1/2 gal per plant per

day)

*would probably also work in recirculatingsystem

Fertilization-


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Fertilization-Magna Gro brand fertilizer consists of:

HydroponicBase Mix -analysis 2-3-6

ingredients: poultry compost tea, pasteurized blood meal, calcium phosphate,

and seaweed. This also contains trace minerals with fermented molasses in the

form of Zn SO4, Mg SO4, and Fe SO4. 19%N from poultry compost tea and pasteurized blood meal

K-9 -9% K2O from seaweed

Organic forms of trace minerals supplied as 6% B, 6% Fe, 6% Mg,and 6% Ca added, as needed based on tissue analysis.

For exact receipe, consult NCSU greenhouse vegetable

website

For other fertilizer sources, consult www.attra.orgwebsite


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Earth Juicebrand fertilizer consists of 5 separate

formulations:(N-P-K)

Grow (2-0.44-0.83): bat guano, Norwegian sea kelp, natural

sulfate of potash, feather meal, oat ran, blood meal and steamed

bone meal Bloom (0-1.3-0.83): bat guano, Chilean sea bird guano,

Norwegian sea kelp, natural sulfate of potash, steamed bone

meal, oat bran and rock phosphate

Catalyst (0.03-0.0044-0.083): oat bran, kelp, wheat malt,

molasses, yeast

Micro-burst(5% Mg, 0.02% B, 0.05% Cu, 0.2% FE, 0.1% Mn

and 0.15% Zn): kelp meal, magnesium sulfate, borax, copper

sulfate, iron sulfate, manganese sulfate, and zinc sulfate. Meta-K(10%K): from seaweed


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Method of addition

Injected into lines during daily

waterings(flush on weekends)

Fertilizers agitated by aquarium

pumps

Filtered to remove some, but not

all solids Pump adjusted to low dilution

rate (1:20)


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New Materials Available, But Untested

Soluble Fertilizers

Natural Organic Grow from JedwardsInternational (organic

fish hydroloysate, OMRI certified)

Harmony Farms Omega 6-6-6 (certification status unknown)

Potting soils McEnroeOrganics

Southland Organic Mix (10% chicken litter compost)

Others: select the database on Organic Amendments at

www.ncsu.edu/organic_farming_systems/or search on

www.attra.org

i


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Many products Available for Home or

Hobby use

B t M N tb P ti li C i l


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But May Not be Practical in Commercial

Production!


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Can Also Use Manure Teas!

Recmmendationsfororganicfertilization


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Recmmendationsfor organic fertilization

of soilless media (peat/pinebark): Constant provision of fertilizers at levels comparable toconventional mix (receipes on website & in newsletter)

pH and salts adjustment to prevent burning

Precautions with drip injection:

Low dilution rates (1:50 or 1:20)

Agitate with pump to prevent settling

Weekly water flush Emitters which resist clogging

Need some filtration, but nutrients not completely soluble

Processed fertilizers rather than fishmeal(too smelly!)


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Unresolved issues in organic

fertilization in our system: Is flavor and quality different?

How do you reduce pH and salts?

Would our recommendations also work on inert

substrates such as perliteand rockwool with low CECand in recirculatingsystems?

How do you increase potassium and calcium? Are there more affordable alternatives?

Will animal waste products work and be allowed?

organic hydroponic greenhouse crop production; by mary peet

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